Pneumatic screen



Spt. 25, 1923.

J. HERMAN PNEUMATIC SCREEN Filed June 1, 1922 4 Sheets-Sheet 1 Sept. 25 1923. 1,469,003

J. HERMAN PNEUMATIC SCREEN Filed June 1, 1922 4 Sheets-Sheet 2 Sept. 25, 1923. 1,469,003

J. HERMAN RNEunlmTIc SCREEN Filed June 1, 1922 4 Sheets-Sheet 5 l$zven OH/V HERMAN.

Sept. 25 1923. 1,469,003 J. HERMAN I PNEUMATI C SCREEN Filed June ll 1922 4 SheetsSheet 4 Patented Sept. 25, 1923.

t ease 'r eeice- JOHNIYIERIYMAN, or os ANGELES, CALIFORNIA.

BN1]UMATIC scanner. Y

Application filed June. 1,

To all whom it. may concern Be it known that I, JOHNHERMAN, a ,cit

izen of the United'State's, residing at Los Angeles. in the county-of Los Angelesand State of California, have invented new and useful Improvements in'Pneun atic Screens,

of which the-following is a specification.

This invention relates screen of economical construction and east of operation and which willbe efiicient, es

pecially, for the separation of finely ground or other material, such, for instance,'asof one hundred mesh fineness.-

An object is to provide an improved screening means and to providefor the-,di

tion of material which is held against the;

screen by air pressure, and to accomplish the removal by the change of the effective pressures of air upon the oversize material.

'Another object is to provide an apparatus in which there is presented a-very large area of screen, in proportion to the are'abfcross section of the draft chamber.-

A further object is to provide a method and apparatus whereby the same may be practiced for the eflicient pneumatic screening of fine materials.

An embodiment of the invention is de-v scribed in the following" specification and illustrated in the accompanying drawings, in which,

Fig. 1 is a front elevation of themachinc, parts of which are broken away to illustrate interior construction.

Fig. 2 is a side elevation of the machine with a feeding conveyor illustrated partly in section. v 7

F1g.-3 1s a vertical SQCtlOIIthIOUgl] the apparatus from front to rear.

Fig, 4 is a plan and partial section of the machine. I V

"Fig. 5 is a detail sectional view showing diagrammatically the screening and draft apparatus and indicating the modes of action thereof. 7

' In its preferred embodiment the machine to pneumatic screens and has for its ob e'ct to provide 1922. Serial No. 565,052.!

includes a' suitable base 2'and frame struca ture, which-latter may consist of upwardly and forwardly extended side frame mem here 3 suitably spaced" in parallel position andcarrying at the upper portion a separat-K ing chamber or box which includes a top plate 4 and a bottom plate 5 angular-1y disposed with respect to the base 2 and to the front of which plates is secured a suitable and, preferably, removable front panel- 6 whiclrmay be fastened as by means of a flanged frame 7 secured by bolts to the contig'uous frame members. 7 V

At the ends of the machine there are suit- Iably journaled oblique shafts 9 and 10 re spectively carrying drums 11 and 12, the latter preferably being of a spring roller type so asto automatically return in one direction to wind up a screening medium. such as a sheet of'fabric 13 appropriately attached to winding curtains 14 fastened to the'drums 11'and12. .l /leans are provided for intermittently drawing. or pulling the screen member 13. from'the spring drum 12 transversely to and fro- Within the separating chamber behind the'front panel 6; The screening member 13 is'ar'ranged in an inclined position upwardly and forwardly and parallel to the front panel 6 and passes through guide slots 15 in "the end walls or frame members 3. To secure a reciprocating movement of the screen member 13 one of the shafts, as shaft 9, is provided with a crank or disc element 16 to which is connected a link 17, thisiinturn being attached to a crank 18 secured on the; end of an upwardly lncliningdriving shaft 19 provided in suitable bearings 20 support ed on the side members of the frame. i

The crank shaft 19 has at its lower end a gear 21 of 'the bevel type engaging; a complementary beveled gear 22 which is secured on "a countershaft 23 supported in bearings" 2 f carried by rearwardly extending bracket arms 25 of the frame.

- Thecountershaift 23 is provided with a pulley 26 engaging a belt '27 driven by a pulley 28 on the shaft of a motor 29. Obviously, other; suitable driving mechanism maybe utilized' to secure rotation of the;

crank shaft 19 so that rotary motion thereof is transmitted intoan' oscillating'motion of I the drumshaft 9 of the drum 11. This oscillating motion results in a winding and unwinding of the flexible curtain 1 1 to which the'screen 13 is secured. On the pulling di verges;

stroke of the drum 11 the screen is drawn in one direction across 1ts chamber and on the reverse stroke the spring drum 12 retracts the slack and pulls the screen 13 in the opposite direction.

The apparatus is designed to operate on a pneumatic principle in which the material to be screened is subjected to a draft or current of air. It has heretofore been proposed to utilize pneumatic means for separation purposes but results therefrom have not been entirely satisfactory for various causes and in the present machine these defects are sought to be overcome by a novel method and construction of devices for effecting the .ower end of the front panel 6 the upper end of the pocket 32 opening throu 'h a' mouth 32 into the chamber formed bhind the front panel 6 and in front of the screen 13. At ti rear of the screen there is provided a back structure consisting substantially of a number ofchannel shaped strips 33, the fianges of which extend forwardly toward the screen 13 and which flanges are also disposed in comparatively close relation but are spaced sufficiently to form' vertically extending channels through which air at atmospheric or increased pressure is designed to pass freely toward the back of the contiguous screen 13. The back members have substantially flat rear wallsand the fla We 33' thereof are shown as slighty so that contiguous flanges of the back members 33 form forwardly tapering nozzles of a shape as indicated at 34, Figs. i and 5. The'back members 33 are arranged with their back webs in a common plane and incline from the top 4: to the bottom 5 of the separating chamber and lie in a position parallelwto the screen 13.

It is preferable that the screen 13 be subcted not only to a reciprocating movement tl e chamber but also toa vibrating moveto and fro concurrently with the remotion. Such a Vibrating motion may conviently be produced as by he followingmeans: The back members 33 are shown as connected at their upper ;o a. carrying beam 35 and at their v1' ends to a c rying beam36; the'back members terminating within the top 4; and the bottom 5 and are, therefore, free to vibrate when actuated by vibrating means. Such means in the illustrated embodiment consists of an eectrical apparatus and includes a olenoid core 37 mounted in a spool 38 having an electric winding 39 to receive,

preferably, an alternating electric current having a well known property of causing a core as 37 to reciprocate in the spool. The solenoid is supported in a. suitable support including a bar' lO having bearing brackets ll which may form a portion of the frame. The inner end of the solenoid core 37 is designed to impinge upon a lever 42 which is pivoted at 43 upon a bearing 44 which may extend inwardly from the back bar 40. The lever 42 extends beyond its fulcrum 43 and is connected as by a link 45 to an attachment secured across the backs of the back members 33. Such attachment may consist of transversely disposed angle strips 16 to which the link 45 is pivoted at 47. The lever 42 has connected at one end a contractile splin --18 tending to push the link 4-5 toward the back members 33 and shift them forwardly and during-operation of the solenoid core 37, this hammers upon the lever 42 at a high rate of speed anda slight vibratory'motion is, therefore,.imparted to the organized or rigidly connected back memhere 33. It will, therefore, be seen that while the tensioncd screen 13 is shifted to and fro across the edges of the nozzle forming flanges 33','these flanges at the same time vibrate slightly with a movement at right angles to the movement of the screen 13, which latter is constant-y pressed against the edges of the flanges 33 by a draft of air.

This draft of air is induced as by means of a blower 50 which conveniently maybe attached to and driven by the motor 29 and has its suction mouth connected to an up. wardly and forwardly inclined throat 51 which terminates at the bottoms of the assembled back members 33, as'clearly shown in Fig. 3. The screen 13 is disposed in front of theupper lip or edge of the throat 51 and when theblower is in operation, suction is created in the throat 51 and behind the screen 13, this suction being establishedin the channels formed in the channel shaped back members 33. The resultant effect is to create suction in the space between the front panel 6 and the screen 13 and this attenuates the air pressure in the feed pocket 32 'so that material chargedthereinto is drawn upwardly into the space behind the panel 6 and i then caused to change its pathof trave from an upwardly ascending line to a rearward flow or line of travel wherein it impinges upon the front of the screen 13.

111 the ascending chamber behind the front panel 6 is disclosed means consisting of split conduits extending along the front of the screen 13'an d registering with the nozzle passage ways 34. Bythig means there is a differential air pressure maintained at successive zones or areas along the screen 13. These conduits are shown as'in the form'of flues 53 of triangular cross section wlth converging rearwardly extending walls spaced toward a gravity door or gate 56 which is yieldingly suspended at its upper end over an outlet 55 of the spout '55.

In operation, the motor 29 drives the transmitting mechanism connected to the screen shfting drum 11 and this alternately winds and releases the screen 13 so that this is shifted while supported, substantially on each face, between the nozzle flanges 33 and the fiues 53. At the same time the vibrating mechanism including the lever 42 shakes the back structure 33 and this causes the'screen 13 to be vibrated to and fro. The blower produces a suction in the throat 30 and in the separating chamber, which draws the ma terial up through the intake mouth 32 from the pocket 32"and the rising material flows upwardly along the front of the screen 13 so that the particles are drawn against the screen in a line substantially perpendicular to its face. The liner material passes through the screen 13 under the effect of the suction in the spaces between the channel members 33 and is drawn down and'into the pump from which it isdischarged into a conveyor tube 50*, Fig. 4. Y. The oversize material will accumulate upon'the front face of the screen 13. During this accumulation the vibration of the screen causes the layer of material to be loosened-so that the mate rial is repeatedly subjected to the suction elfect of the draft through the screen, thereby enabling all of the material of a prede termined size to pass through the screen which rejects the oversize. During the vi- 'bration of the screen it is shifted with a longitudinal motion on its own length so that zones of the curtain are during operation alternately subjected to the suction effeet and also'to an atmospheric pressure effect; this latter being obtained as air tends to flow through the several nozzles or spaces 34 into the opposite slit flucs 53 which are fixed in the separating chamber as above de scribed. In other words, the layer of accumulated oversize material, and also such fine material as may not have passed through, is constantly being scraped-by the opposed nozzle members and shifted into new positions bythe shifting of the screen 13 bodily with respect to the atmospheric pressure nozzles. The oversize material being ultimately rejected passes down into the discharge chute 55 where it accumulates behind the gravity gate 56' until such a quantity has been gathered as will overcome the weight of the gate 56 and'this tending to impel them through the screen 13.

will be swung'to van'opening position allowing a portion of the accumulated oversize-- material in the bottom of the chute 55 to flow out. immediately after which thegate 56' resumes the normal closed position. Obviously, the discharge action will be intermittent and will continue while the machine is in operation. I

From the above it will be seenthat by the combined vibrating actionand the shifting motion of the screen member 13 the layerof material on the. front face thereof will be successively changed in position and the area of the screen will be atcertain portions subjected-Yto suction pressure and at 0 intermediate portions to atmospheric pressure andfthese pressures Wlll be intermittently alternated so that all particles of material will be subjected repeatedly to forces As the oversize particles are brought into the zones registerin with the atmospheric pressure nozzles 34, the oversize-material will be subjected to a reverse acting pressure, and will be loosened and may freely. fall through the discharge flues 53 to the chute 55, this latter and the. flues'being at atmospheric pressure. 7

It is obvious that this general principle of l operation may be secured, when it is desired, V

forthe treatment of materials to be screened i by subjecting them to liquid as well as to air. as the inipelling agent, In such case, the screen and its coordinate. mechanism would. preferably, be arranged in a horizontal plane. 7

Various modifications and changes -may be resorted to within the spirit of the invent-v tion as claimed. 1 1 I 'What is claimed is:

1. The method of screening fine material. which consists in directing material to be screened in an upward path of movement in airand then changing the direction of move ment by a. suction effect to impinge it upon" f an upright screening medium, concurrently reciprocating in the direction of its length. and having vibratory movement to the medium. 7

2. The method of screening fine material,

fine material, which consists of directing the material to be screened by and with'a current of air against an upstanding screening 7 medium, and alternately;present zones of he de g the material que and can i s of material so as to i 'ih a ted meter tin cl y 111 an obh 9 71 eudiculer aeeumula edlum to diff portion of t means.

creening' 11 ]80 ehi turn 11 per; r face of an 0b 3. he method of s eh consists in sub u of e fluid V rdi u'f su anguim partic hieteriai tie:

upwa tin the it euree of the them Wit iew 1011 the uu-d l iedium.

be screened to a fluid current bV which V in is cites a cut- In to sure is me'u e 1 or t d e by and wit g A 0: th

press e and pre.

pressure one err 1 air the medium to difierent'degrees'of air preseccumuiatei eheinne 1 sup the under siz dium m and the loudireetien rep0s1tmgeurrent.-

11mg fine mm a supply chemmediu 1 nd e suetien from the and means side of the material and -finder reeni g fine a supply um and e ite side, means 11 the suppi er, whereby rmvn from eeiproeating 1 movement islodge the r dine on the receiving side of th tion chamber, Whereby't is d e material and 5 the under size pass through the the dlum to agitutien g in a awn drum and 11 through the screeni si n he same whereby to pass threug h it for so g medium the medi the oppos nt flow ction eha be screened drawn throuqh the means for 112m with a longltu schnrge fines hevii mouths dispesed ad acent the 1 or scree edium the e side, means for inent flow from the su eve? he epposit presenting the me lnai mo'veme ing scrape or d iere] 111 said scrs ein f means inect ereenmp; ssure eeti g i .2 i

paratus' reenin de of f over six 1 freed aeo gpera d me 101' reci i he receiv ge d um etteetlve to e seine W 7, be free one si mheron he s to uaterial i lever 0 em on one sic cuc pre rse to the d 13. E n a! he sue st-"sa tive to scrape 01: dislodge the acan a 1211, a so med r on t longi fee ed lever 0 te ucing a curre chamber to t ply against said inediu ize ated tubular r lever 01" A i t to e Screened 'is di? 1. l, to ftil'ltia rial is draw means [iii].

materia 11in" iiig ium and subj ening medium,

net ciu -.rrausz'ed 0n us chamber 0n suet ere he in means arm medi 0 agitate t I dueinn" a eur pi again dium uuuer i 8 9 L 8 r on e u LL 1 S C ber terlei cum materi scr the

accumui gitudihai iqu L medium sure, the iy in 01 rent.

an 0b the as material e materiel erentie hcurrenti ue eezz aceuniulate "sted and 100smule: to dif" JjGC I 1 )Werd tlu the SCIQL-ii! zsists iii sh iec 1 Aid). 00

which the screen;

screening medium, and means for directing a fluid current into each of the discharge lines, whereby to reject the over size material on the screening medium.

15. In an apparatus for screening fine material, a screening medium, a supply chamber on one side of the medium and a suction chamber on the opposite side, means for inducing a current flow from the supply chamber to the suction chamber, whereby the material to be screened is drawn from the supply against said medium and the under size material is drawn throughthe screening medium, means for reciprocating the medium witha longitudinal movement, means arranged on the receiving side of the medium effective to scrape or dislodge the acciimulated layer of over size material and to agitate the same whereby the under size material may be freed to pass through the screening medium, said scraping means including tubular discharge flues having longitudinal mouths disposed adjacent the screening medium, mean for directing a fluid current into each of the dis-charge fiues, whereby to -reject the over size material on the screening mediiim,and means for vibrating the medium concurrently with its longitudinal reciprocations.

l6. Ina screening apparatus, a screening niedium,means for effecting a flow of material to be screened from a supply toward the screening medium and for drawing the under size material through the screening. medium, discharge means for the over size material arranged on the supply'side of the screening medium, means for longitudinally reciprocating the screening medium, and means for vibrating the screening medium concurrently with its reciprocating movemerits.

17. In a screening apparatus, a screening medium, means for effecting a flow of mate rial to be screened from a supply toward the screening mediumand for drawing the under size material through the screening medium, discharge means for the over size material arranged on the supply side of the screening medium, means for longitudinally" medium; discharge means for the over size material arranged on the supply side of the screening medium, means for longitudinally reciprocating'tl e screening medium, means for vibrating the screening medium concurrently with its reciprocating movements, means for effecting zone being alternatelysubjected to the di'fierential pressures during reciprocation so that the collected over size material on the said mediumis agitated and'dislodged and the under-size material freed to pass through,

said discharge means consisting of fines having longitudinal mouths arranged close to t-he'receiving side of the screening mediiiiii. and means on the'discliarge side of the medium disposed contiguous there to and forming nozzles registering withthe said fines, whereby differential pressure is created atthe zones of the screening. medium alternately presented to the mouths differential current H pressures in zones aloiig'the screen, each,

of the dischargc'flues into which-there ,jected material is released and thereby dis charged; V p v 19. In an apparatus for screening fine material, 7 a screening medium, a supply chamber and a suction chamber, means for inducing a current-flow from the" supply chamber to the suction chamber, whereby the material to be screened is drawn from 7 the supply against saidmediuni and the under size mater al is drawn through the screening medium, means for. reciprocating the medium with ailongitiidinal movement, and means arranged on the receiving, side of the medium effective-to scrape or dislodge the accumulated layer of over material andto agitate the same whereby -the under size material may be freed to pass through thescreening medium. 7 V r 20. In an apparatus for screening fine material, a screening medium, a supply chamber and a'siiction chamber, means for indiic ing a current flow-from the supply chamber to'tlie suction chamber,- whereby the niaterial to be screened is drawn from the supply size against said medium and the under size material is drawn through the screening medi-' uni, means for reciprocating the medium with a longitudinalmovement, and means arranged on the receiv ng side of. the medium effective to scrape or dislodge the accumulated layer of oversize material. V v

V, 21. In an apparatus for screening fine ma terial, a screening medium, a supply cham:

her and a suction chamber, means for induc ing a current flow from the supplychamber to the suction chamber, whereby the material to be screened is drawn from the supply against said medium and the under size material is drawn through the screening me} dium, means for reciprocating the, medium,

means arranged on the receiving side of the medium effective to scrape or dislodge the reciprocating ma w a sore ning lllSCll'llH, a supply 'chamhercn one side of the medium and a suction chamber on the opposite side, means for incncing a current flow from the supply chamber to the suction chamber, whereby the material to be screened name-11 from the supply against saidmedium and the under size ii'-ite1.'ialf is drawn through the screening ,Clllllil, me 'i'or reciprocating the medium with 'a longitudinal movement, means arranged the rfececving side 01 the medium effective to scrape or dislodge the accumulated layer o'fover size material and to agitate the same whereby the under size material may be freed to'pass through the screening medium, and means for vibrating the medium concurrently with its'longitudin'a'l reciprocationsi 1 i 23. In a screening apparatus, a screening medium, means foreiiecting a flow of mate- "ial to be screened from a supply toward the screening medium and for drawing the under size material through the screening medium, discharge means for the over size ma terial, means for longitudinally reciprocating the screening medium, and means for iihrating the screening medium concurrently with its reciprocating movements.

In screening apparatus, a screening mediuimineans for effecting a flower material to be screened from a supply toward the screening medium and for drawing the under size material throu h the screening medium,"discharge means tor the over size material arranged'on the supply side of the screening medium, means for longitudinally the screening medium, means for-vibrating the screening medium concurrently with its reciprocating movements, and means for effecting differential current pressures in Zones along the screen.

25. In a screening apparatus, a screening medium, means for effecting EtjfiOW' ofmaterial to be screened from a supply toward dium, dischr the screening inediumYand for drawing the under size material through the screenin .ifitlllllll, discharge means for the over rci v cone hem rercntial so that" ely subjected to the during reciprocation led over size naterial on is agitated and dislodged charge means c 1 nsistingoi e tudinal mouths arranged side'ot the screening s fon the discharge side jzones along the screen,

size'material freed to pass cin'dispcsed "chntiguous thereto i discharge fiuesinto which the rejected mate rial is released and thereby discharged,

In a screening apparatus, a screening inediunnnieans for e fl ect in'g a new of material to be screened from a' supply toward the screening medium and for drawing tlieunder siie material through the screening mee means for tl e o rer. size material, means i for, longitudinally reciprocatmg the screening medium, means for vibrating the screening V its reciprocating more nents, means iior st fecting di'ti'erentialc r at pressures in Zones along the screen, eac "zone being alternately subjected to the all? i ing reciprocatibn sothat the collectedover size materialon the said medium is agreed and dislodged and the under size material freed to" pass ensign, said discharge means consisting of fines having longitudinal mouths arra ged c'lose to the'r eceiving side of the scre ning medium and means onvthe discharge side ofthe'me diiim disposed contiguous thereto amhfcrmiiig nozzlesregisteriing with the said fines. p I

In testimony whereof I'have signed my name to au mentation; i V

' Jonu'nnnnnn erenti'al' pressures dur- 

